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Description

I designed a robot based on Arduino using Bitlash as a command line interpreter. Then I embedded code lines in RFID cards and tested with kids. It has been delightful to try it with young kids. So far the age that I proved it to work the best is 4 to 7 years old.

Right now I am working with an ESP8266 chip and making my own over-the-air update platform. This way different parents or teachers can exchange games they designed for kids. For this I am porting Bitlash to the ESP and running a small local server that initiates it as an AP and then switches to STA.

I am planning to release both hardware and software as an open source project. My current models are all 3D printed, so I think it will be easier for others to reproduce.

Details

We are having a serious issue with the rechargeable batteries right now. I am thinking about switching to 4 x AA batteries. But it will still be a bit glitchy when they are not well charged.

Also on the 3D model we have one issue with the arms that don't allow them to move correctly. For some reason everything looks good but after assembly they get locked and they can't move even a bit. My impression is that there is to much pressure applied to the gears.

Work in progress ! I am happy to say that the games played with the kids are a complete success. But there are some small issues with the new cards / syntax that we invented as game rules:

6 movement cards

Play card to execute the code

Pause / Reset cards

Function 1 & Function 2 (can work recursively between each other)

IF sound / IF movement / IF distance is close / IF distance is far

variable store

As you can see, I borrowed as much as I could from Scratch software. Nevertheless it's already the first set of instructions and we get over 20 cards. What is really inconvenient for the kids, there are too many cards in your hands and it becomes difficult to play. Still many things to figure out...

It has been a frustrating experience for the last 6 months or so to go to the assembly line. So many things went wrong that every time I talk with the people in the factory I am already in a defensive position, expecting them to bring more bad news.

You will notice that sometimes now I will start using singular instead of plural. I virtually received no help from anyone that expressed interest in finishing the production and delivering the rewards. I had to pay to reprocess all PCBs and the endless list of problems that appeared during assembly. Design problems don't appear till you start production. It looks good, you hacked one or two or ten units. But then the mold doesn't fit the parts you specified, the electronics don't work as expected and the robots don't move as you programmed.

One of the saddest decisions was to glue the arms of the Plobots. Another critical moment I thought I was going to faint was when I realized that the construction bricks wouldn't fit on the back of the Plobots. I think that the rest of my remaining hair felt when I noticed that one in ten Plobots was able to scan the RFID cards.

But now I also have good news, I tested last week about 200pcs with an acceptance ratio of 0.8. This is the first time I see that finally we will be able to have the Plobots being shipped. That is super low but I will use the rest of the 0.2 I will use them for demos locally.

We opened the mold finally. And outsourced the PCB to a studio. That was not a minor effort. They added an USB type C charger that is really fancy (and also almost drove me crazy because of EMI)

I also had some trouble tuning up the PID constants. The motors we got from the supplier were just too different from the ones we originally designed Plobot with. But, oh, well... it works!

It's fair to share that there is an amazing article that helped me to understand the coding structure that was used to implement the PID inside of the turning of Plobot. Here is a detailed PDF explaining it.

We got our latest design printed with SLA and you can tell the difference really. One of the issues to solve was interference with the ultrasound sensor. Here you can see how it looked before and the modification we introduced.

BTW, less technical, but we already surpassed the 50% of our Kickstarter campaign at http://ks.plobot.com ! Thanks for the support!

We are at the stage of getting feedback from parents and other teachers. Many things happened. Among them, a mom not convinced that we were not ready to sell yet, tried to bribe me saying outrageous prices. Interesting human behavior, it seems that her daughter really liked Plobot !